AIDS

AIDS

The acquired immunodeficiency syndrome (or AIDS) was first recognised in USA, and the association of human immunodeficiency virus (HIV) as the cause of development of AIDS was established later on in 1984.

Initially, some cases of severe opportunistic infections e.g

Pneumocystis carinii pneumonia and unusual neoplasms, such as kaposi’s sarcoma, which can only be seen in severely immunocompromised patients i.e in defective

Cell-mediated immunity-were found in some previously healthy homosexual individuals

In the absence of any know cause of underlying immune defects this condition was then eventually recognised as the ‘acquird immunodeficiency syndrome’ or AIDS.

Aetiology:

AIDS is caused by infection with human retroviruses known as human immunodeficiency virus (or HIV or HIV-1).

Besides classic AIDS virus, a group of related viruses designated as HIV-2 -  found in some west African patients having same genetic organization as HIV-1, but significantly different glycoprotein contents, manifested AIDS-like illnesses in some patients, but most cases found asymptomatic.

Mode of transmission:

1. Sexual contact is the major mode of transmission of HIV. About 60% are homosexual bisexual.

2. Intravenous route- about 20% of patients are heterosexual men and women intravenous drug users, and is related to the sharing of needles.

About 7% are homosexual or bisexual men, who are also using intravenous drugs.

Transfusion of contaminated blood and blood products, if not screened or treated may be a significant way of AIDS transmission.

3. Infected mothers are efficiently (30-40%) transmit the virus to their infants parentally during the first and second trimester. Virus can also be transmitted from mother to infant via breast feeding.

Incubation period:

  Incubation period is about 2-4 weeks following infection.

Diagnosis:

1. ELISA test-diagnosis is confirmed by detection of antibodies to  HIV by ELISA test. Blood specimen should be handled carefully. It becomes positive with 5months of infection.

2.  Detection of virus-by circulating viral protein assays.

3.  complete blood count (CBC)-usually anemia; neutropenia and thrombocytopenia are found in advanced HIV infection.

4.  Absolute CD4 lymphocyte count and percentage- a person with a positive HIV serology and a CD4 lymphocyte count below 200 cells/     or a CD4 lymphocyte percentage below 14% is to be considered as a patient of AIDS.

 Antiretroviral treatment-

The antiretroviral agents that are in clinical use now a day, play their role by suppression of HIV replication. A considerable suppression of HIV replica-tion may cause partial immunologic reconstitution &improvement of immunosuppression. as a result, the patient get stabilization and improvement of clinical course of the disease.

Initiation of antiretroviral therapy depends on different clinical situations. Such as, an adult patient should be initiated therapy only when any of the following indications is present-

-symptomatic HIV disease

-CD4 counts <350 cells/ul

-very rapidly falling CD4 count

-high viral load (> log 4)3

There are several guidelines and treatment frameworks developed (e.g PACT framework, BHIVA guidelines) for retroviral therapy is to be given must be individualized depending on the clinical condition of the particular patient.

The antiretroviral drugs available now-a-day, are classified into three main categories-

1. Nucleoside and nucleotide reverse transcriptase inhibitors-

(a)  Zidovdine

(b)  Didanosine

(c)  Zalcitabine

(d)  Stavudine

(e)  Lamivudine

(f)  Abacavir

(g)  Adefovir

2. Nonncleoside reverse transeriptase inhibitors-

(a)  Nevirapine

(b)  Delavirdine

3. Protease inhibitors

(a)  Indinavir

(b)  Nelfinavir

(c)  Ritonavir

(d)  Saquinavir